Methods and apparatus for monitoring components of downhole tools

ABSTRACT

Disclosed herein is a surface controlled subsurface safety valve (SCSSV) that includes a moveable component of the SCSSV and a stationary component of the SCSSV. A sensor element is also included which is configured to sense position of the moveable component relative to the stationary component. Further disclosed herein is a method for sensing position of an object which includes placing a component comprising magnetostrictive material in a location calculated to be contacted by a separate component and causing a stress on the material with the separate component. The method further includes measuring a change in magnetic permeability of the material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of an earlier filing date from U.S. Provisional Application Ser. No. 60/618,826 filed Oct. 14, 2004, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

Downhole tools having movable components, such as but not limited to surface controlled subsurface safety valves (SCSSV) are ubiquitously utilized and sometimes mandated in the hydrocarbon exploration and recovery art. Both safety systems and simply exploration or production devices could be improved by enhancements in means to monitor the positions thereof.

Using SCSSV's as a particular example, it is important for an operator to have knowledge of the position and/or condition of SCSSV's for various reasons. Traditionally, such knowledge has been gained by monitoring flow volume from the well and control line pressure at the surface. These methods work well in instances where the well is operating correctly and where the SCSSV is not an excessive distance from the source of the control signal. Where operating parameters of the well are not ideal however, and/or the SCSSV is a substantial distance from the source, such as in sub-sea applications, traditional methods for adjudging the position of the valve are suspect and cannot be relied upon. Doubt in this regard for any downhole tool is generally the initiator of lost time and potentially unnecessary expense. Uncertainty is never beneficial to the hydrocarbon industry; better means of determining things such as SCSSV position/condition will be welcomed by the art.

SUMMARY

Disclosed herein is a downhole tool that includes a moveable component and a stationary component. A sensor element is also included to sense position of the moveable component relative to the stationary component.

Further disclosed herein is a method for sensing position of an object which includes placing a component comprising magnetostrictive material in a location calculated to be contacted by a separate component and causing a stress on the material with the separate component. The method further includes measuring a change in magnetic permeability of the material.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings wherein like elements are numbered alike in the several figures:

FIGS. 1A and 1B are schematic views of a closure member and a stationary element in open and closed positions of a valve;

FIG. 2 is a schematic view of a closure member with a torsion spring and sensor;

FIG. 3 is a schematic view of a closure member with an alternate sensing arrangement;

FIG. 4 is a schematic view of a flow tube in a housing with a sensor arrangement between the power spring and the spring stop;

FIG. 5 is a schematic view of a flow tube in a housing with a sensor arrangement at both ends of travel;

FIG. 6 is a schematic view of a piston of a valve and a sensor arrangement to indicate position throughout travel; and

FIG. 7 is a schematic view of an alternate embodiment of the concept of FIG. 6;

FIG. 8 is a schematic view of another alternate embodiment of the concept of FIG. 7;

FIG. 9 is a schematic view of a closure member with a single-position sensing arrangement; it is an alternate embodiment of the concept of FIG. 1.

DETAILED DESCRIPTION

Obtaining more knowledge about downhole tools can be occasioned, even in real time, by careful and creative positioning of sensory devices. In some embodiments hereof, the sensing device(s) comprise a magnetostrictive material such as Terfenol-D commercially available from Etrema Products, Inc. The magnetostrictive material exhibits different magnetic permeability when placed under stress, and particularly compression, than it does when not under stress. Magnetic permeability is measured by supplying a current to a coil around the magnetostrictive material. This property is reliable and repeatable and the material itself is highly robust making Terfenol-D a useful sensing material for downhole tools. It is to be appreciated that Terfenol-D is but a single example of a magnetostrictive material and that others with similar properties could be substituted. In the exemplary embodiment of Terfenol-D, reference is made to U.S. Pat. No. 6,273,966 which is fully incorporated herein by reference, wherein Terfenol-D is described in more detail. In the event a check is desired, a second magnetostrictive device is deployed in proximity to the first but which is not exposed to the stress creator intended to be measured. Any permeability change due to conditions not related to the stress creator being measured will register on both devices, making resolution of the target stress creator clear and reliable. In other embodiments hereof permanent magnets, hall effect sensors and mechanical, electrical or optical limit switches or optical readers may be employed. In each embodiment the goal is to obtain more direct and rapid indication of a particular condition or position of a device downhole, such as for example one or more of the components of a SCSSV. It is also to be understood that one or more of the types of sensors may be employed in the same device and one or more of the same type of sensor may be employed in the same devices.

Referring to FIGS. 1A and 1B a schematic representation of a closure member (such as a flapper valve) portion of a SCSSV is used to illustrate the inventive concept, which as stated above applies to other tools as well. The closure member portion of the SCSSV is illustrated generally at 10. The closure member is disposed in a housing 12 which includes a sensor element 14. The element 14 is configured to sense pressure exerted thereon by a cam surface 16 of closure member 18 (flapper). The closure member pivots around pin 20 and based upon position will exert pressure on element 14 or will not exert pressure on element 14. FIG. 1A illustrates the device 10 in a valve closed position and FIG. 1B illustrates the device 10 in the valve open position. In the open position of FIG. 1B, it is apparent that cam surface 16 has come into contact with sensor element 14. In the event sensor element 14 is a magnetostrictive material, a change in magnetic permeability of sensor element 14 will be measurable to provide an indication that the flapper 18 is indeed open. Other sensor elements can be substituted such as magnetic sensors, hall effect sensors, switch type elements, etc. (FIG. 9) which all would be positioned as is the illustrated magnetostrictive sensor element 14. Information obtained by sensor element 14 is communicated to a remote location such as a surface location by a communication means (not shown) such as a hydraulic conduit, electrical conductor, optic conductor or wireless method.

Referring now to FIG. 2, shown is an illustration of a flapper valve 18 which is actuated to close by at least one torsion spring 22. As the arrangement is illustrated, two torsion springs 22 are apparent although it is to be understood that a single torsion spring is also contemplated. Each of the illustrated springs 22 include a leg 24. In one embodiment, at least one of the two illustrated legs 24 rests upon a magnetostrictive material 26 such that upon opening the flapper 18, the magnetostrictive material 26 is placed under a greater compressive load occasioned by the tightening of torsion spring 22. It is to be understood that both illustrated legs 24 could be placed on one portion of material 26 or individual portions of material 26. Compressive stress at material 26 causes altered magnetic permeability thereof, which property is remotely readable by current charge. In another embodiment, similar to the foregoing embodiment, magnetostrictive material 26 may be substituted for by a switch member where the benefits of the magnetostrictive material are not needed.

Referring now to FIG. 3, another alternate embodiment is schematically illustrated. Flapper 18 is pivotally connected at hinge pin 20 to flapper housing 12. As illustrated SCSSV 10 includes sensors to verify both the open and closed positions of the flapper 18. To this end, flapper 18 is endowed with a high temperature magnet 28 while housing 12 includes a “closed” sensor 30 and an “open” sensor 32. Sensors 30 and 32 are sensitive to a magnet in proximity thereto and thus can verify a closed or open position of flapper 18 due to magnet 28 coming into proximity to sensors 30 and 32, respectively. In one embodiment, the magnet 28 is of permanent type and the sensors 30 and 32 are Hall-effect.

Sensors 30 and 32 are informationally connected to sensor electronics 34 which are programmed to interpret what has been sensed and emit a signal to be propagated to a remote location along schematic cable 36, which may be hydraulic, electric, optic or wireless in configuration.

Referring now to FIG. 4, one of ordinary skill in the art will appreciate a schematically represented flow tube 41 within a housing 42. The flow tube 41 is moveably positioned by a piston 66 and this movement is resisted by a power spring 43, the stationary end of which is fitted with a sensor substantially similar to that described in conjunction with FIG. 2. In one embodiment, the end of the power spring 43 rests upon a magnetostrictive material 26 such that upon opening the SCSSV, the magnetostrictive material 26 is placed under a greater compressive load occasioned by the compression of power spring 43. Compressive stress at material 26 causes altered magnetic permeability thereof, which property is remotely readable by current charge. In another embodiment, similar to the foregoing embodiment, magnetostrictive material 26 may be substituted for by a switch member where the benefits of the magnetostrictive material are not needed.

Referring now to FIG. 5, one of ordinary skill in the art will appreciate a schematically represented flow tube 41 within a housing 42 and limited in axial movement by a top sub 44 and a bottom sub 46. This illustration is limited to a flow tube and housings relevant thereto but should be understood to be some of the components of a SCSSV. The illustration has been done in this way to more readily show the sensor elements 48 and 50. In this embodiment, verification is available for position of the flow tube 41 in the “open” position or the “closed” position by receiving a signal from sensor element 48 or sensor element 50. In either position one of the two identified sensors will be fully loaded while the other will be fully unloaded. Where neither is loaded, the tube is in mid-stroke and where both are loaded there is significant indication that one or both sensors are malfunctioning. Based upon exposure to the foregoing embodiments described herein, one will appreciate that the sensor elements 48 and 50 may comprise magnetostrictive material functioning as noted above, or mechanical, electrical or optic switches.

In yet another embodiment, referring to FIG. 6, a magnetic or optical sensing device 60, such as a hall effect sensor or optical “bar-code” reader, is positionable within a piston housing 62 operably near piston 66 with magnetic or optical indicator 64 running down the side of piston 66 such that the amount of movement of indicator 64 mounted to piston 66 can be measured as it passes device 60. As the indicator 64 is fixedly mounted at piston 66, the movement of indicator 64 is the same as the movement of piston 66. Alternatively, a row or column of individual units of magnetostrictive material can be utilized to register variable positioning of the piston 66 or other moving device in near or real time. This occurs by altering magnetic permeability of the column or row in sequence. Direction of movement and speed of movement are resolvable in this way.

Referring now to FIG. 7, a magnetic sensing device 60, such as a hall effect sensor, is positionable within a piston housing 62 operably near piston 66 with magnetic indicator 64 mounted at a single position on piston 66 such that the movement of piston 66 can be measured as it passes device 60. As the magnetic indicator 64 is fixedly mounted at piston 66, the movement of indicator 64 is the same as the movement of piston 66.

Referring now to FIG. 8, the same arrangement as described in FIG. 7 is illustrated with sensing element 60 located in a hole 61 in piston housing 62 (and as illustrated filling the hole such that the hole is not separately visible in the drawing) running parallel to and located in proximity to the primary piston 66.

Referring now to FIG. 9, a schematic representation of a closure member 18 (such as a flapper valve) portion of a SCSSV is illustrated generally. The closure member includes a magnetic element 70 positioned such that as the closure member 18 pivots around the flapper hinge 20 and moves into the full-open position the element 70 comes into contact with the sensing mechanism 72 mounted on sensing bracket 74. The sensing mechanism registers the change in magnetic field and transmits this information such that a “full open” signal is sent to the surface.

It is important to understand that all of the above embodiments are exemplary in nature and that the concept of positioning a sensor element relative to a moveable and stationary component to sense relative position of the two components is applicable to all tools that include a moveable and stationary (or even another moveable) component. These include such as sliding sleeves, cross-over tools moveable service tools, any type of safety valve, open/close sleeves, etc.

While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation. 

1. A downhole tool comprising: a moveable component of the downhole tool; a stationary component of the downhole tool; and a sensor element configured to sense position of the moveable component relative to the stationary component.
 2. A downhole tool as claimed in claim 1 wherein the sensor element is a magnetostrictive material having predictable change in magnetic permeability when stressed.
 3. A downhole tool as claimed in claim 1 wherein the sensor is a hall effect type sensor.
 4. A downhole tool as claimed in claim 1 wherein the sensor is a mechanical switch type sensor.
 5. A downhole tool as claimed in claim 1 wherein the sensor is a optical sensor.
 6. A downhole tool as claimed in claim 1 wherein the moveable component is a closure member.
 7. A downhole tool as claimed in claim 1 wherein the moveable component is a flow tube.
 8. A downhole tool as claimed in claim 1 wherein the moveable component is a piston.
 9. A downhole tool as claimed in claim 6 wherein the closure member includes a cam surface configured to bear against the sensor element in one of an open condition and a closed condition of the closure member.
 10. A downhole tool as claimed in claim 8 wherein the piston includes a magnet and the stationary component supports the sensor element which is configured to sense the magnet.
 11. A downhole tool as claimed in claim 6 wherein the closure member supports the sensor element such that the sensor element is in communication with a torsion spring locating against the closure member.
 12. A downhole tool as claimed in claim 11 wherein the sensor element is in communication with a power spring.
 13. A downhole tool as claimed in claim 1 wherein the sensor element is two sensor elements, one positioned at one end of the travel of the moveable component and the other positioned at another end of travel of the moveable component.
 14. A downhole tool as claimed in claim 13 wherein the sensors are carried by the moveable component.
 15. A downhole tool as claimed in claim 14 wherein the sensors are carried by the stationary component.
 16. A method for sensing position of an object comprising: placing a component comprising magnetostrictive material in a location calculated to be contacted by a separate component; causing a stress on the material with the separate component; and measuring a change in magnetic permeability of the material.
 17. A method for sensing position for an object comprising: placing a magnetostrictive material in a location, the location including a coil; applying a current to the coil; measuring magnetic permeability of the material; and comparing measured magnetic permeability to known permeability of the magnetostrictive material in an unstressed condition.
 18. A method for sensing position for an object as claimed in claim 17 where the method further comprises: determining whether the material is stressed to conclude a position of the object in one of in contact with the material and spaced from the material. 